If you’re planning to go boating this weekend, you’ll be safer if you leave the beer at home.

The U.S. Coast Guard’s annual report, Recreational Boating Statistics, shows that a boat operator or passenger with a blood alcohol content above the legal limit has an increased risk of getting into a boating accident. Here’s why:

Sun, wind, noise, vibration and motion—stressors common to the boating environment—intensify the effects of alcohol, drugs and some medications by causing fatigue, which impairs a boater’s balance, coordination and reaction time.

Alcohol reduces inhibitions and brings on a false sensation of physical warmth, which could cause a person to enter or remain in cold water until hypothermia sets in.

With these impairments, accidents are more likely and more deadly for passengers and boat operators. Alcohol is a factor in nearly 1 in 5 recreational boating fatalities; Coast Guard data show that in more than half of these cases, the victims capsized their boats or simply fell overboard.